1. Field of the Invention
The present invention relates to a light emitting device, and more particularly, to a semiconductor light emitting device integrated with a protection diode against an electrical discharge such as static electricity.
2. Description of the Related Art
A semiconductor light emitting device is useful in terms of a high output, excellent light efficiency and reliability as a light source, and thus, research into a semiconductor light emitting device capable of being substituted for a backlight in a lighting device or a display device as a high output and a high efficiency light source has been actively undertaken.
In general, a semiconductor light emitting device includes an active layer able to emit light by the recombination of electrons and holes between and together with a p-type semiconductor and an n-type semiconductor. Such semiconductor light emitting devices may be classified according to a position in which an electrode is located to form a semiconductor layer or according to a current path, and although they are not particularly limited, the classification thereof may be determined depending upon whether or not there is electrical conductivity in a substrate mainly used for a semiconductor light emitting device.
For example, when a substrate having electrical insulation is used, mesa etching to form an n-type electrode connected to an n-type semiconductor layer may be required. That is, portions of a p-type semiconductor layer and an active layer are partially removed to expose a portion in an n-type semiconductor layer region, and a p-side electrode and an n-side electrode are respectively formed on a top surface of the p-type semiconductor layer and an exposed top surface of the n-type semiconductor layer.
In the above-mentioned electrode structure, a light emitting area may be reduced during the performing of a mesa etching process and may be formed in a direction perpendicular with regard to current flow, thus it is difficult to promote uniform current distribution throughout an overall area, which may cause a reduction in light emission efficiency.
Meanwhile, when a conductive substrate is used, the conductive substrate may be used as a side electrode. In this semiconductor light emitting device structure, there is little light loss in a light emitting area as compared to the former structure, and a uniform current flow may be comparatively secured herein, whereby light emission efficiency can be enhanced.
However, in a case in which the light emitting device is implemented to have a large area in order to obtain a high output, uniform current distribution is carried out throughout an entire light emitting area by providing an electrode structure such as an electrode finger thereto, but in the case in which the conductive substrate is used, limitations on light extraction due to an electrode provided on a light emission surface or light absorption by the electrode is caused, thus degrading light emission efficiency.
In addition, a semiconductor light emitting device may be exposed to a momentary high voltage such as an electrostatic discharge (ESD) while operating the device, so a function of the device may be damaged.
A design to avoid damage is therefore required. Principally, a scheme in which a specific protection diode is added is considered, but in this case, a separate diode should be packaged and disposed in a single package space, thus causing an obstacle in miniaturizing a product.